There have been ongoing efforts to develop improved 5th-Generation (5G) communication systems or pre-5G communication systems, in order to satisfy wireless data traffic demands that have been on the rise since commercialization of 4th-Generation (4G) communication systems. For this reason, the 5G communication systems or the pre-5G communication systems are referred to as Beyond-4G-Network communication systems or post-long term evolution (LTE) systems.
In order to achieve a high data transmission rate, implementation of the 5G communication systems in a mmWave band (for example, 60 GHz band) is being considered. In order to mitigate the path loss of radio waves and to increase the propagation distance of radio waves in the mmWave in connection with the 5G communication systems, technologies such as beamforming, massive multi-input multi-output (massive MIMO), full dimensional MIMO (FD-MIMO), array antennas, analog beam-forming, and large-scale antennas are being discussed.
Furthermore, in order to improve the system network in connection with the 5G communication systems, technologies such as evolved small cells, advanced small cells, cloud radio access networks (cloud RAN), ultra-dense networks, device-to-device communication (D2D), wireless backhaul, moving networks, cooperative communication, coordinated multi-points (CoMP), and interference cancellation have been developed.
In connection with the 5G communication systems, besides, there have been developments of hybrid frequency shift keying (FSK) and quadrature amplitude modulation (QAM) modulation (FQAM) and sliding window superposition coding (SWSC), which are advanced coding modulation (ACM) schemes, and filter bank multi carrier (FBMC), non orthogonal multiple access (NOMA), and sparse code multiple access (SCMA), which are advanced access technologies.
A wireless communication device for 5G communication may support communication in the mmWave band on the basis of a multi-antenna (for example, MIMO) structure. To this end, the wireless communication device may include a radio frequency (RF) module that supports communication in the mmWave band on the basis of a multi-antenna (for example, MIMO) structure. The RF module is, in general, configured as an integrated circuit (IC). The IC is also referred to as a “chip”.
The RF may not always be able to provide the performance, which has been set as the target during design, due to variations in the process, voltage, and temperature (PVT). This is because characteristics of elements (power amplifier (PA), low noise amplifier (LNA), mixer, LO, ABB, etc.) that constitute the RF module may be varied by environments, parameters, etc.
Therefore, the wireless communication device may perform calibration regarding the RF module, in order to maintain operations that exhibit stable performance. The calibration may be an operation of adjusting the tuning parameters of the elements (PA, LNA, mixer, LO, ABB, etc.) that constitute the RF module such that the RF module can operate and exhibit the performance that has been set as the target during design. For example, the wireless communication device may perform calibration adaptively when the same is powered on, or when a change in performance of the RF module is sensed.
In the case of a wireless communication device that supports the mmWave band, the RF module is, in general, implemented by two separate chips for the purpose of efficient mounting. For example, such a structure may be proposed in which the RF module is separately implemented as a front RF module (RF front-end integrated circuit (IC), RFA) and a rear RF module (ABB IC, RFB), and the RFA and the RFB are connected using a single coaxial cable.
However, it may be difficult to implement a loop back path for phase calibration in the case of a wireless communication device equipped with an RF module structured such that the RFA and the RFB are connected using a single cable. For example, almost all wireless communication devices that support the mmWave band adopt the time division multiple access (TDMA) scheme, and thus cannot perform transmission (TX) and reception (RX) simultaneously. As a result, the wireless communication device cannot simultaneously perform transmission and reception of a test signal for calibration, and it is therefore not easy to measure the performance of the RF module and to calibrate the phase on the basis thereof.
Therefore, it has been requested that, in connection with a wireless communication device that has a multi-antenna including a plurality of antenna arrays, a method be provided for calibrating the phase regarding an RF module structured such that a plurality of front RF modules and rear RF modules are separated from and connected to each other by a cable.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.